Recommend extensions when opening notebooks

[DonJayamanne]

For #5577

[codecov-commenter]

Codecov Report

Merging #5690 (06b06f7) into main (aa2f524) will decrease coverage by 3%.
The diff coverage is 87%.

❗ Current head 06b06f7 differs from pull request most recent head a0f2e64. Consider uploading reports for the commit a0f2e64 to get more accurate results

@@           Coverage Diff           @@
##            main   #5690     +/-   ##
=======================================
- Coverage     72%     69%     -4%     
=======================================
  Files        401     402      +1     
  Lines      26741   26807     +66     
  Branches    3901    3910      +9     
=======================================
- Hits       19453   18549    -904     
- Misses      5641    6641   +1000     
+ Partials    1647    1617     -30     

Impacted Files	Coverage Δ
src/client/datascience/jupyter/kernels/helpers.ts	71% <75%> (-2%)	⬇️
src/client/datascience/extensionRecommendation.ts	87% <87%> (ø)
src/client/common/utils/localize.ts	95% <100%> (+<1%)	⬆️
src/client/datascience/serviceRegistry.ts	97% <100%> (+<1%)	⬆️
...ascience/notebookStorage/notebookModelEditEvent.ts	10% <0%> (-50%)	⬇️
...ce/raw-kernel/liveshare/kernelSpecNotFoundError.ts	50% <0%> (-50%)	⬇️
.../client/datascience/plotting/plotViewerProvider.ts	38% <0%> (-48%)	⬇️
.../datascience/plotting/plotViewerMessageListener.ts	15% <0%> (-47%)	⬇️
...nt/datascience/jupyter/kernels/kernelSelections.ts	50% <0%> (-45%)	⬇️
...ience/variablesView/variableViewMessageListener.ts	55% <0%> (-45%)	⬇️
... and 82 more

[IanMatthewHuff]

language in comment

[IanMatthewHuff]

Looks good. One possible suggestion would be telemetry on the prompt. Knowing how much it's shown and what the users pick. Not sure if we care though.